Google Books
Used by 2 peoplebooks.google.com ↗
“I pushed to have Google focus on creating good and free to the world genealogy data sets (as part of the Google Books project) while I was there, but nobody was interested.”
Erica Joy Baker Interview, Senior Engineering Manager (Patreon), Diversity and Inclusion Advocate · via Uses This 
“I'm also on Google Books all the time, poring through centuries' worth of public domain books and magazines.”
David Malki ! Interview, Designer, cartoonist (Wondermark) · via Uses This